Medical imaging is critical for quality health care for early detection and efficient treatment of disease and injury. In 1970s, when MRI became a clinic tool, it was enthusiastically embraced by the hospitals. These hospitals, having since moved from systems of 0.5 T to 1-1.5 T, now target 3 T. However, ~20,000 MRI units now in service worldwide benefit only ~10 % of the total humanity, chiefly in the urban areas of the developed nations. One direct and quick way to redress this glaring disparity and unfairness in medical treatment opportunities is to develop low-cost and easy-to- operate MRI systems. For a vast majority of humanity, low-cost 0.5-T superconducting MRI units would be beneficial and should also help to reduce health care costs in the U.S. Compared with the critical temperatures ( Tc ) of NbTi (~10 K) and Nb 3Sn (~18 K), Tc ~40 K of MgB2 promises obvious advantages. Owing to a higher Tc, an MgB 2 magnet will have its stability considerably enhanced and cryogenic system substantially simplified. Based on the technologies developed in the original project, we propose to complete, at the conclusion of Phase II, a whole- body fully functional MRI magnet of 0.5 T. In this Phase I project, we will address issues, which were not investigated in the original project. In Phase I, our focus will be on the fabrication of MAIN COIL that will be operated in persistent mode. We will address the issues of conductor (particularly performance consistency in long lengths), protection, and temporal stability. In Phase II, we will incorporate a set of correction coils to transform the Phase I system to a fully functional MRI model magnet. With the cryocooler-SN 2 approach demonstrated in the original project and to be reconfirmed by the Phase I system, the magnet can operate continuously without liquid helium. Significance of the program is further advancement in the following design/operation issues for HTS magnets: 1) using MgB 2, to keep the HTS magnet low-cost;2) operating at around 10--15 K for enhanced stability;3) liquid cryogen free "dry''environment;4) persistent-mode operation for good temporal stability and ease of operation;5) protection from quench damages. In addition, the cryogenic approach will allow the system susceptible to power disruptions, expected in many rural communities in the U.S. and underdeveloped nations. We strongly believe that Phase II MRI magnet will become a model of low-cost, easy-to-operate MRI magnets suitable for rural and underdeveloped region. The technologies accumulated in the project will also promote the application of MgB 2 for MRI magnets of even higher field competitive to the current state-of-the-art NbTi magnets, but with substantially lower costs, enhanced stability, and without reliance on liquid helium supply. PUBLIC HEALTH RELEVANCE: The specific aim of this 2-phase renewal project is to complete, at the conclusion of Phase II, a whole-body fully functional MRI magnet that will become a model for low-cost and liquid-helium-free commercial units for small hospitals, rural communities, and underdeveloped nations. These MRI magnets should contribute to early detection and efficient treatment of disease and injury among a large mass of humanity. They would also contribute to reduced health care costs in the U.S.